1. Field of the Invention
The present invention relates generally to electronic indicator and control devices and more particularly to an improved indicator and control device which can be attached to a printed circuit card in situ externally connected thereto and then used to control and indicate certain operations of the board without requiring that it be disconnected from the motherboard.
2. Description of the Prior Art
Complex electronic devices typically are comprised of subcircuit modules constructed as plug-in circuit board "cards" which are easily removable for replacement and repair. The problem is that in most such electronic apparatus, the cards are arranged in closely packed space-saving rows which make it difficult to obtain access to the cards for testing without removing the card from the motherboard.
One way to enable the operation of a board to be inspected without removing it from the containing apparatus is to mount an indicator and control device to an external edge of the board such as is disclosed in the co-pending U.S. patent appplication of Ralph J. McComas, Ser. No. 894,714, Filed, Apr. 10, 1978, the subject matter of which is hereby corporated by reference into this application. However, in practice it has been found that electrical interconnect between the indicator and control device and the circuit card frequently requires the addition of level setting and biasing resistors and other elements which cannot be conveniently added to either the circuit card or the indicator and control device.